Fiber optics use thin strands of glass called optical fibers to transmit light signals over long distances. An optical fiber consists of a core surrounded by cladding that reflects light internally through total internal reflection. Hundreds or thousands of fibers are bundled in cables. A fiber optic system includes a transmitter that encodes light signals, the optical fiber that conducts the signals, and a receiver that decodes the signals. Fiber optics offer advantages over copper wire including lower costs, higher data capacity, immunity to electromagnetic interference, lighter weight, and non-flammability.

1. How Fiber Optics Work
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2. 1. Introduction to Fiber Optics Work
You hear about fiber-optic
cables whenever people
talk about the telephone
system, the cable TV
system or the Internet.
Fiber-optic lines are strands
of optically pure glass as
thin as a human hair that
carry digital information over
long distances. They are
also used in medical
imaging and mechanical
engineering inspection.

3. 2.What are Fiber Optics?
Fiber optics are long, thin strands of very pure glass about the
diameter of a human hair. They are arranged in bundles called optical
cables and used to transmit light signals over long distances.
[Parts]:
[Core] - Thin glass center of the fiber where the light travels
[Cladding] - Outer optical material surrounding the core that reflects
the light back into the core
[Buffer coating] - Plastic coating that protects the fiber from
damage and moisture
Hundreds or thousands of these optical fibers are arranged in bundles
in optical cables. The bundles are protected by the cable's outer
covering, called a jacket.

4. 3.How Does an Optical Fiber Transmit
Light?
● The light in a fiber-optic cable travels
through the core (hallway) by constantly
bouncing from the cladding (mirror-lined
walls), a principle called total internal
reflection. Because the cladding does not
absorb any light from the core, the light
wave can travel great distances.
However, some of the light signal
degrades within the fiber, mostly due to
impurities in the glass. The extent that the
signal degrades depends on the purity of
the glass and the wavelength of the
transmitted light (for example, 850 nm =
60 to 75 percent/km; 1,300 nm = 50 to 60
percent/km; 1,550 nm is greater than 50
percent/km). Some premium optical fibers
show much less signal degradation -- less
than 10 percent/km at 1,550 nm.

5. 4. A Fiber-Optic Relay System
●Fiber-optic relay systems
consist of the following:
●[Transmitter] - Produces and
encodes the light signals
● [Optical fiber] - Conducts the
light signals over a distance
●[Optical regenerator] - May be
necessary to boost the light
signal (for long distances)
●[Optical receiver] - Receives
and decodes the light signal

6. 6. Advantages of Fiber Optics
* Less expensive - Several miles of optical cable can be made cheaper than equivalent lengths of
copper wire. This saves your provider (cable TV, Internet) and you money.
* Thinner - Optical fibers can be drawn to smaller diameters than copper wire.
* Higher carrying capacity - Because optical fibers are thinner than copper wires, more fibers can be
bundled into a given-diameter cable than copper wires. This allows more phone lines to go over the
same cable or more channels to come through the cable into your cable TV box.
* Light signals - Unlike electrical signals in copper wires, light signals from one fiber do not interfere
with those of other fibers in the same cable. This means clearer phone conversations or TV reception.
* Low power - Because signals in optical fibers degrade less, lower-power transmitters can be used
instead of the high-voltage electrical transmitters needed for copper wires. Again, this saves your
provider and you money.
* Digital signals - Optical fibers are ideally suited for carrying digital information, which is especially
useful in computer networks.
* Non-flammable - Because no electricity is passed through optical fibers, there is no fire hazard.
* Lightweight - An optical cable weighs less than a comparable copper wire cable. Fiber-optic
cables take up less space in the ground.